Tension device for shears.



G. A. PARKER.

TENSION DEVICE FOR SHEARS.

APPLIOATION FILED OCT. 28, 1909.

Patented Apr. 5, 1910.

A TTORNEK a n umammm SHEMVHOONUTOLUM co wvuvun a Mzmw Elli I STA GEORGE A. PARKER, 03? PHILADELPHIA, PENNSYLVANIA.

TENSION DEVICE FOR SI-IEARS.

To all whom it may concern:

Be it known that I, GEORGE A. PARKER, a citizen of the United States, residing at Fhiladelphia, in the county of Philadelphia and State of Pennsylvania, have 111- vented a certain new and useful Improved Tension Device for Shears, of which the following is a specification.

This invention relates to that class of shears or scissors in which an arched springbar is arranged on the outside of one of the blades and by which pressure is applied through the shears-pivot to yieldingly hold the edges of the shears together in making a cut.

Considerable difliculty has been experi enced in this class of shears or scissors with regard to the loosening of the thumb nuts that look the parts together due to the vibrations of the cutting blades that are imparted to the pivot-bolt.

The principal object of the present invention is to provide simple, efficient and comparatively inexpensive means whereby the above-reeited disadvantageous feature may be eliminated and in the providing of the novel combination and arrangement of parts as Will hereinafter more fully appear.

The invention consists of the improvements hereinafter described and finally claimed.

The nature, characteristic features and scope of the invention will be more fully understood from the following description taken in connection with the accompanying drawings forming part hereof and in which z- Figure 1, is a perspective view of a pair of shears or scissors embodying the invention, Fig. 2, is an edge elevation of the same, Fig. 8, is a longitudinal mid-section of Fig. 2, cutting axially through the pivot, and drawn to an enlarged scale, Fig. 4-, is a cross section taken upon the line H of Fig. 2, and drawn to an enlarged scale, and Fig. 5, illustrates in perspective the various parts going to make up the tension elements of the shears.

In the drawings, the shears or scissors 1, are made up of blades and handles of any well-known and usual construction according to the purposes for which the shears or scissors are intended. The two blades are apertured at the pivot point in a smooth circular manner and through the same a pivot-bolt 2, is introduced. This pivot-bolt Specification of Letters Patent.

Application filed October 28, 1909.

Patented Apr. 5, Serial No. 525,140.

| consists of a solid cylindrical member externally screw-threaded as at 3, at one end and terminating in and having formed integral therewith at its opposite end a washer-like portion 1, that rounds or swells out into a screw-head The threaded end 3, of this pivot-bolt 2, is split longitudinally for a portion of its len 'th as at (3, for a purpose to be presently described. This pivotbolt is also squared as at 7, longitudinally thereof, throughout its entire length (see Fig. 4) the purpose of which will also presently appear.

The screw-threaded end 3, of the pivotbolt is adapted to receive when in proper position a washer 8, a thumb nut 9, and a jam nut 10. Upon the outside of one of the blades of the shears or scissors is applied a spring bar 11, apertured as at 12, for the passage therethrough of the pivotbolt 2, the portion 13, of said aperture being squared to cooperate with the squared portion '7, of the pivot-bolt 2 (see F ig. in order to prevent the said springbar from rotating upon the surface of the blade to which it is attached. This spring-bar is adapted to bear againstthe blade beneath the parts 1 and 5, of the pivot-bolt 2, hereinbefore referred to, the forward end of the spring-bar taking a broad bearing upon the blade and the rear end thereof being preferably tapered and taking a bearing in a cavity 14., in said blade.

The blades of the shears or scissors being assembled upon the smooth portion of the pivot-bolt with the spring-bar in proper position, the washer 8, is passed freely over the screw-threaded end of the pivot-bolt 2, and the thumb nut 9, screwed to place thereon thus clamping together the respective parts of the shears. In this connection it may be remarked that the screw-threaded end of the pivot-bolt 2, being split as at G, the split parts thereof have the tendency to spread outward. This is particularly true if the split 6, has been made by a wedgeshaped tool. This tendency of the pivotbolt to spread serves to securely hold in position the thumb nut 9. This is important be cause as the shears or scissors are used, the movements of the spring-impelled cutting blades impart more or less vibration to the pivot-bolt and serve to loosen the thumb nut. However, by splitting the end of the bolt as described this tendency toward loosening of the thumb nut through vibrations is eliminated. 10 further hold the 1111111113 nut 9, from loosening, the 1am nut 10, is provided.

Obviously the split end of the bolt also serves to firmly clamp the 121111 nut with re- 1 1 a ain nut abut-ting thereagainst said nuts spect to the thumb nut.

What I claim is is a new article of manufacture shears or scissors comprising a pair of blades having smooth circular pivot bolt receiving openings, a spring-bar having a similar opening slightly squared arranged upon one of the blades a pivot bolt having a longitudinally disposed squared portion to fit the squared opening in said spring-bar passing through said openings said pivot bolt having a head abutting against the spring bar at one end and having a projecting externally screw threaded and longitudinally disposed split port-ion atits opposite end, a thumb nut, and

being fitted over said projecting threaded bolt the split portion thereof serving to spread within and beyond the nuts to lock them against movement through vibration. In testimony whereof I have hereunto signed by name.

GEO. 1. PARKER. Witnesses lioness SWEENY, E. Hume W'nsox. 

